Assimilation
by Desert-sands
Summary: Yugi is pretty good at games. But he never thought he'd find himself in a virtual world inside what he thought was a normal arcade game. Nor did he think he'd find himself faced against his partner in a game of life or death.
1. System Acquired

_Once again I find myself inspired by a piece of artwork I saw. I haven't written a crossover before so I hope this goes well! It's a definite work in progress, but I hope you enjoy._

_I own nothing in YuGiOh or Tron._

_Reviews are greatly welcomed!_

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The electronic whirring and music was like heaven after a long day at school. Taking a deep breath, Yugi sighed, lips spreading into a grin. This was glorious.

"New arcade?" Came the voice from the spirit who floated beside him. His own cool eyes barely contained his own excitement as he followed his aibou's gaze.

"Yeah! Well, newly re-opened. It was closed years ago but whoever bought it fixed it up and opened it again!" Yugi smiled at him. "But enough of that, ready to play?"

Yami chuckled, it was hard to not get excited when the boy was practically bouncing up and down and nearly vibrating with energy. He was so ready to take on those high scores. "Let's go!"

He took off, running first to a game that they both knew, taking turns to try and beat each others scores, then to a newer game that he had only heard about. On it went, the next few hours spent with laughter, friendly banter and game after game of fun.

Yugi leaned back with a satisfied grin as the victory music played from his latest challenge. How perfect this was turning out to be, all these games and Yami? Sighing contently, he looked around for the next game to occupy there time. Blinking he turned.

"Something wrong?"

"Hm?" Yugi looked over at him. "Oh I just...didn't notice how quiet it was this far in to the arcade..." He looked at the unoccupied games. Well, they were older so that may have been why. That was a shame, some of the older style games could be the most fun. Even if they didn't have as good graphics as the new stuff, they were more...authentic? He couldn't really put a word to it.

"Want to go back to the front?" Yami hadn't noticed it, but Yugi was right.

"Nah, it's fine. I was just thinking how some people just don't appreciate these games, that's all." He smiled and wandered down through the isle of games, rubbing his growling stomach.

"Hungry?" The spirit looked at him with slight concern.

"Just a little...How about a snack, one more game, and then home?" He didn't want to go home yet, but he knew there was no way to play all the games in one day. The place was too big. But it wasn't going anywhere, they could come back the next day after school again.

"That sounds like a plan," Yami smiled. "There's a vending machine over there."

Yugi turned the corner and went up the to machine, putting in some change and getting a candy bar. Humming softly he wondered what game should be their last for the day. Bending, he got his snack and straightened, tearing the package as he did so. But he froze, eyes tracing the blue glow in the reflection of the vending machines glass.

Turning, he took in the game behind them. Yes...This was their game. Stepping up to it, he put in the needed money...And began playing. He had to admit, he hadn't expected the kind of game for its design. But soon...It was over and he was staring at his name on the score board. Damn...Why did he have to pick a game that was pretty short? Oh well, sighing he picked up his backpack before something caught his eye.

"Aibou? You okay?"

"Yeah just...Hold on," he stood and ran his hand along the back of the game where the seam should have been between it's metal and the wall.

Should have.

"That's weird..."

"What?" Yami was thoroughly confused at this point as he followed him.

"It's part of the wall...They tried to make it look like one of the other games, but it's connected into it." Walking around it, he examined it, running his hand along the other side. Until his fingers pressed along a spot that hinged in. With a cracking sound, the wall separated to his left and he jumped back, nearly falling over his backpack. Yami immediately stood in front of him, ready to take over if he had to.

"No, no it's okay!" Yugi looked around, making sure no one heard them before getting back to his feet and dusting himself off. Going up to the door he tugged it open further, the entire panel swinging slowly forward with a soft scraping sound.

"Yugi...Wait, I don't know about this." Yami reached out to touch his shoulder, looking past him into what little of the darkened hallway they could see.

"But...Mou hitori no boku..." Yugi turned to look at him. "It's a secret door!"

"I see that..." He, too, was curious but...What if it was something dangerous? "We don't know what's beyond that door. Nor do we know if we _should _go past it. It was hidden for a reason...And last I checked snooping wasn't a good thing."

"Please? Just a little peak...it could be an adventure! It could hide some secret or treasure! Please please pleeease!" He was nearly on his knees. Gods he wanted to see what could possibly be hidden in such a sneaky way.

Yami let out a sigh. "Okay, one quick look but stay close and if anything happens, I'm taking over, got it?"

"You got it!" He grinned and pulled the door open further, enough for him to squeeze in. Looking around he coughed, the air was pretty stagnant and he wondered how long the place had been closed up. He was silently glad it was dimly lit, since there were no windows and he tentatively looked around a corner, pretty aware of Yami hovering over his shoulder.

"Oh woah..." The computer was covered in a thick layer of dust, but there was no mistaking what it was. He was at the desk in a matter of steps, brushing the dirt and grime from the glass top. It lit up instantly at his touch, a keyboard and screen coming to life. "Why would someone hide this back here? This is so cool!"

"Yugi...be careful..." The spirit looked at the machine warily. The games out in the arcade were fun. Simple. This thing...It looked way too complicated to be for children.

"I know, mou hitori no boku... But look at this. I wonder if Kaiba knows about it...It might be an abandoned project of his."

A series of beeping drew Yami's attention to behind them. What in the name of Ra...

"I can't believe this was here!" Reaching out, Yugi touched the computer screen gingerly. The computer seemed to be taking a breath for the first time in a long while, coming back to life and blowing the dust from it's system as it charged up, the lights becoming brighter and brighter...The hairs suddenly stood up on the back of his neck.

_Download in progress_

"YUGI!" He acted quickly, the puzzle blazing to life as Yami stood behind the smaller boy, eye of horus lighting up on his forehead. Lifting his hand he shielded him, his own magic meeting the beam of light that was shot towards them from what must have been connected to the computer.

For a split second, there was a blinding light as the energies fizzled together.

_Downloading..._

"YAMI!" Yugi shielded his eyes, the power of the blast knocking him back against the desk. The computer sang as the light began to dim. Then...

Silence.

Squinting, he opened his eyes. Waiting to be blinded again. But he was met with the same dimness as when they entered. But with the added absence of a spirit.

"...Mou hitori no boku?" He looked down at his puzzle. Had he...But he wouldn't have just...Would he?

"Yami?" Panic began to well up in him as he looked around. Where had he gone? Where _could _he have gone? He was connected to the puzzle! His eyes landed on the contraption that was across the room behind where he had been standing. Amethyst gaze followed the wires, widening as a cold feeling began to seep down his spine. He turned to the computer.

_Download Complete_


	2. User Logged On

"No no no..." His fingers flew over the keyboard, eyes scanning the screen. Pressing anything, everything he could think of. Trying to undo what he must have done.

_DATA CORRUPTED_

"Come on..." Clenching his jaw he cursed himself. How could he have let this happen? Damn his curiosity. Damn it!

_DATA CORRUPTED_

"Give. Him. Back."

_DATA CORRUPTED_

His fists slammed onto the console, shoulders shaking as tears stung his eyes. What had he done? The utter silence on the other end of their link was like a cold black hole that gaped at him.

"Yami..." His voice quivered, eyes shut tight as he tried to control himself. He couldn't break down. He couldn't. It wouldn't help him anyway, tears wouldn't bring him back.

But despite his best efforts, the tap, tap, tap of his tears landing on the desk was the only sound as he tried to breathe.

Calm down, calm down, calm down.

It was a mantra he repeated over and over. What could he do though? He wasn't a hacker like Kaiba and why would he help him? Not to mention...He didn't want to leave Yami behind. But what choice did he have? He couldn't figure out the computer, not alone. Sniffing he lifted his head and stared at the screen as it scrolled through data. Taking a deep breath he straightened.

"I'm sorry..." He murmured, fingers brushing over the cool screen. "But I'll be back." He promised, even if Yami couldn't hear him.

Picking up his backpack, he turned and left the secret room. His feet pounded the sidewalk as he ran. After a quick call to his mother, he was staying at Joey's, and it wasn't a complete lie...He was heading there now, after all.

"Joey!" He called as he pounded the door. Gods, please be home... "JOEY!"

"Alright alri-!" The door swung open and Yugi almost rumbled into his wide-eyed best friend. "Yugi? Why're you tryin' to beat down my door?" The blonde shook out his wet hair, the damp towel still around his neck. At least he had thrown on clothes.

"Joey I...Something happened...Computer...Arcade...I...I need help." Yugi looked up at him frantically, he could barely breathe from the building panic and running. Tears were welling up again and he clenched his hands into fists.

"Woah, easy there, Yug. Take a breath." Taking a step back, he let his best bud in. He didn't know what was going on, but whatever happened had him extremely upset. "You okay? Someone after ya?" He narrowed his eyes as he looked past him to the street before closing the door. If anyone had laid a hand on him, there'd be hell to pay.

Yugi leaned back against the wall, only able to shake his head as he tried to catch his breath.

"Here..." A cool can of soda was pressed into his hand and he looked up. When had Joey left the room? He shook his head again and took a couple swigs. He gave Joey credit for his patience as he waited for him to calm down enough to form a coherent sentence.

Leading Yugi into the living room, he sat him down and crossed his arms once he seemed to be getting oxygen into his lungs. He had said no one was after him, but still Joey's eyes looked him over, making sure there were no cuts or bruises. He had that spirit to protect him, but still. Anything could happen.

"Okay, spill. What happened." He said. It was less a question, more a demand of an explanation. Yugi stared at the can clutched in his hands. Where to even start? Taking a deep breath, his gaze lowered still to his feet.

"I...I lost Yami," and he launched into his story. From the arcade to the game, to the hidden room, to the computer and the flash of light. He tried to keep himself strong but to his dismay, he his control began to crumble, tears falling down his cheeks as he stood and paced. When he finished, he had his back to his friend.

"How could I do this, Joey?" He scrubbed his eyes. "I was supposed to help him, protect him like he protected me...And I got him taken away from me because I couldn't control my curiosity."

"Hey, it isn't your fault." The blonde duelist went up to him, resting his hand on his shoulder. He found the entire thing hard to understand but he knew two things for certain: stranger things have happened to them, and Yugi was definitely not to blame. "You didn't know what that thing could do. Whoever heard of a computer zapping people? Well, normal people. Who knows what Kaiba does behind closed doors with his machines."

"But what am I gonna do? I...I couldn't fix it. I couldn't undo it...I've never seen a computer like that one and I just don't know what to do." He looked down at his watch. Four hours. It had been four hours since he lost Yami. Looking over his shoulder at Joey he sighed. "I'm so lost."

"Don't worry Yug, I'm sure we'll figure it out. Come on," Joey turned and tossed the towel onto the couch and pulled on his shoes.

"What?"

"We're going back to the arcade."

"Right now?" Yugi turned to him, going to his side.

"Yeah, right now. Because this can't wait. Who knows what happened to Yami and you're upset. I know you well enough to know I shouldn't tell you wait and sleep on it, because you wont. So we're going now." The blonde stood and looked at him. Yugi felt relief begin to wash over him. He wouldn't have to do this alone...They were going to fix it.

Twenty minutes later, they were walking in to the arcade.

"Hey kids, we're closing in a half hour." They looked over to the counter where the man working was looking at them over a newspaper.

"'Kay sir, my bud here wants to show me one of the new games he played earlier." Joey nudged Yugi's shoulder and he nodded in turn. The guy shrugged and went back to reading. "Lead on, pal."

Leading Joey back to where the arcade game, the blue lights were flashing again, begging to be played. He glared at it for a moment, gods if he had never seen that blue Tron sign none of this would have happened. Walking around the side, he prodded the side until he found the switch again to open the door.

As they entered, it closed behind them and he looked at Joey. "You sure about this? We'll probably be in here all night."

"Hey, I'm all set. Don't worry about me." He ruffled his hair. "Anything for my best friend."

For the first time since Yami had disappeared...He smiled. He could always count on Joey. With a nod he went up to the computer again, tapping the console to make it instantly light up. There was an intake of air behind him.

"Woah..."

"Yeah...it was pretty amazing at first." But now he glared at it. It had taken his other self. And he wanted him back. His fingers flew along the keys, trying once again to do something, anything. They switched back and forth, whenever ones fingers started cramping and they needed a break.

Two hours later...

_Command confirmed_

"What...?" Joey stood, he had been sitting on the floor with his back against the desk. "We actually did something?"

_Download ready..._

A chill ran down Yugi's spine as he stared at the screen. Wait...

"Yug?" The blonde looked at him. The smaller cleared his throat and nodded.

"We did..."

"And what's that mean?" He shifted his weight...Something wasn't right. And he didn't like the look in Yugi's face. He knew that determination.

But Yugi stayed quiet, mind slowly working over the options. But there was something he had begun to come to terms with with each passing minute. There was nothing they could do to get Yami out. Not from here. But maybe...Just maybe...

"Hey, Jo?"

"...Yeah?"

"Look here," he pointed at a serious of buttons he pressed. "That's what I pressed to get to this. Keep trying variations like that."

"Okay...What are you going to do then..."

"I'm going to get Yami." Realization slowly seemed to set into his friend.

"Yug, wai-"

But he pressed confirm...And he pushed Joey out of the beam of light.

_Download complete_

Joey looked, wide eyed at the now empty spot where Yugi had been. His eyes lifted to the computer screen as he stumbled to the desk, eyes never leaving the glowing words that flashed. "Yugi...You crazy jerk..."

_Player 1, added._

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_Thank you all for reading! _

_Reviews are awesome, this is a trial run so let me know what you think! _

_Chapter Three should be up by next week!_


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